ASHRAE Terminology

assembly of equipment for the simultaneous control of air temperature, relative humidity, purity, and motion. Compare to air-conditioning system.

the process of treating air to meet the requirements of a conditioned space by controlling its temperature, humidity, cleanliness, and distribution.

useful net, available refrigerating capacity of an air conditioner for removing sensible and latent heat from the space being conditioned.

combination of all components required to provide air conditioning.

in enclosed spaces, combined treatment of the air to control, as specified, temperature, relative humidity, velocity of motion, and radiant heat energy level, including consideration of the need for removal of airborne particles and contaminant gases. Some partial air conditioners that may not accomplish all of these controls are selected for their capability to control specific phases of air treatment.

assembly of equipment for air treatment to simultaneously control its temperature, humidity, cleanliness, and distribution to meet the requirements of a conditioned space. See air conditioner.

air conditioner whose refrigerating system has an air-cooled condenser.

characteristics of the environment. For example, temperature, relative humidity, pressure, and motion.

the effective coil surface temperature when there is dehumidification. This is the temperature to which all the supply air would be cooled if 100% of the supply air contacted the coil. On the psychrometric chart, this is the intersection of the condition line and the saturation curve, where the condition line is the line going through entering air conditions with slope defined by the sensible heat ratio ([gross sensible capacity]/[gross total capacity]). (Also see gross sensible capacity and gross total capacity.)

model based on first-principles engineering methods that provides information on the energy-using systems in a building (heating, ventilation, and air conditioning; lighting; occupancy; plug loads; building envelope). The model, along with weather data, serves as the input data for a specific computer building energy simulation program. When run, the computer simulation program will estimate the energy use and demand in the described building for a time interval specified in the building energy model. Depending on the kind of simulation program and how it is set up to run, various kinds of output may be produced.

available capacity of an air conditioner for removing sensible and latent heat from the space to be conditioned (Btu/h).

an assembly consisting of a heat pump or air conditioner, a desuperheater, a water heater, and if required, a potable water pump, the assembly provides space conditioning and domestic hot water.

(1) adjustment of the fuel rate and air/fuel mixture ratio in response to heating load and flue gas air condition over the full range of the burner capacity from some preset minimum to 100%. (2) device or series of devices that control the flow of fuel and combustion air in the desired ratio to provide efficient combustion.

treating air to control its temperature, relative humidity, cleanliness, and distribution to meet the comfort requirements of the occupants of the conditioned space.

single, functional element forming a part of a ventilation or an air-conditioning installation.

a unitary air conditioner, for a computer and data processing room, consisting of one or more assemblies that include a DX evaporator or chilled-water cooling coil, an air-moving device, and air-filtering devices. The air conditioner may include a compressor, condenser, humidifier, or reheating device.

liquid formed by condensation of a vapor. In steam heating, water condensed from steam, in air conditioning, water extracted from air, as by condensation on the cooling coil.

see packaged air conditioner.

A demand response activity by which the program administrator remotely shuts down or cycles a customer's electrical equipment (e.g., air conditioner, water heater). Direct load control programs are primarily offered to residential or small commercial retail customers.

centralized facility for generation and distribution of the heating and cooling and/or power needs of a community, rather than individual heat or cold generators (i.e., furnace or air conditioner) at each residential, commercial, or institutional site.

replacement refrigerant that has thermodynamic properties similar to one being replaced and does not require air conditioning or refrigerating equipment to be replaced but may require modifications.

systems that primarily use a combination of mechanical equipment, airflow, water flow, and electrical energy to provide heating, ventilating, air conditioning, filtration, humidification, and dehumidification for the purpose of human comfort or process control of temperature and humidity.

the equipment, distribution systems, and terminals that provide, either collectively or individually, the processes of heating, ventilating, or air conditioning to a building or portion of a building.

the total useful capacity of the air conditioner for removing water vapor from the space to be conditioned.

(1) (brine cooler) product of the mass rate of water or brine flow and the difference in enthalpy of the entering and leaving water or brine, expressed in heat units per unit of time. It is expressed also by the total refrigeration effect less the heat leakage losses. (2) (condensing unit capacity) rate at which heat is removed from outer media by a refrigerant in the low-pressure side or by the difference in total enthalpy between refrigerant liquid leaving the unit and the total enthalpy of the refrigerant vapor entering it. (3) (packaged air conditioners) rate at which heat is removed from the airstream, as measured entering the cooling coil and leaving the unit. (4) rate at which heat is removed by the primary refrigerant from the cooling medium (secondary coolant) that is used to transmit the refrigerating effect.

triatomic form of oxygen, O3. Sometimes used as an oxidant in air conditioning and as an odor eliminator in cold storages or exhaust stacks. It is toxic in concentrations of 1 ppm and higher.

(also known as self-contained unit), complete air-conditioning unit, including refrigeration compressor, cooling coils, fans, filters, automatic controls, etc., assembled into one casing.

a factory selected wall sleeve and separate unencased combination of heating and cooling components, assemblies, or sections. It may include heating capability by hot water, steam, or electricity and is intended for mounting through the wall to serve a single room or zone.

(1) heating a food product prior to a subsequent treatment. (2) in air conditioning, to heat the air ahead of other processes. (3) to heat the water prior to heating by the auxiliary thermal source.

packaged terminal air conditioner (PTAC)

comes from internal heat sources. It is used for space heating, domestic or service water heating, air reheat in air conditioning, process heating in industrial applications, or other similar purposes. Recovered heat may be stored for later use.

air conditioning as applied to private houses or apartments.

air removed from a space to be recirculated or exhausted. Air extracted from a space and totally or partially returned to an air conditioner, furnace, or other heating, cooling, or ventilating system.

system of air conditioning in which packed beds of crushed stone or gravel are used for both evaporative cooling and heat energy storage.

packaged air conditioner mounted on a roof, the conditioned air being discharged directly into the rooms below or through a duct system.

a test facility consisting of a room-side compartment and an outdoor-side compartment, each of which is equipped with instrumented reconditioning equipment. The output of this equipment is measured and controlled to counterbalance the room-side net total cooling effect of the air conditioner under test.

the total cooling output of an air conditioner during its normal annual usage period for cooling divided by the total electric energy input during the same period in consistent units (analogous to the SEER but in I-P or other consistent units).

any air conditioner or heat pump that has three major assemblies separated from each other. The compressor would be in a first assembly, with one refrigerant heat exchanger in a second assembly, and the second refrigerant heat exchanger in a third assembly.

see packaged terminal air conditioner (PTAC).

any air conditioner or heat pump that has two major assemblies separated from each other with both assemblies being indoor. The compressor and one refrigerant heat exchanger would be in one assembly, with the other refrigerant heat exchanger in a second assembly.

any air conditioner or heat pump that has two major assemblies separated from each other between indoor and outdoor. The compressor and one refrigerant heat exchanger would be in one assembly, with the other refrigerant heat exchanger in a second assembly.

room air conditioner designed for mounting in window.